Molten metal reactors

ABSTRACT

A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/581,656, filed Oct. 19, 2009, now U.S. Pat. No. 8,309,049, issuedNov. 13, 2012, the disclosure of which is hereby incorporated herein inits entirety by this reference.

GOVERNMENT RIGHTS

This Invention was made under a Cooperative Research and DevelopmentAgreement between Western Hydrogen, LLC and Battelle Energy Alliance,LLC under Contract No. DE AC05ID14517, awarded by the U.S. Department ofEnergy. The U.S. Government has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to a molten metal reactor and, moreparticularly, to a molten metal reactor capable of producing hydrogen,carbon monoxide, and carbon dioxide gases from a carbon-based material.The present invention also relates to a method of forming hydrogen,carbon monoxide, and carbon dioxide gases using the molten metal reactorof the present invention.

BACKGROUND OF THE INVENTION

Methods of converting carbon materials and steam into hydrogen, carbonmonoxide and carbon dioxide gases using a molten metal compound areknown in the art and described in, for example, U.S. Pat. No. 3,252,774to McMahon et al. and entitled Production of Hydrogen-Containing Gases,incorporated herein by reference. Briefly, a carbon material and steamare brought into contact with a molten metal compound within a moltenmetal reactor. When the carbon material and steam are contacted with themolten metal compound, the carbon material and steam are converted to agas comprising carbon monoxide, carbon dioxide, and hydrogen. Any metalsor impurities within the liquid hydrocarbon may be trapped within themolten metal compound.

A consistent issue with molten metal reactors is providing the necessarycontact time between the carbon material to be reacted and the moltenmetal compound. As such, molten metal reactors may be long and contain asubstantial quantity of the molten metal compound and it may be costlyto heat and maintain the molten metal compound at the desiredtemperature. Another problem common with molten metal reactors is theproduct gas stream may comprise some of the molten metal compound. Anymolten metal compound in the product gas stream may damage and corrodeequipment and piping in processing the product gas stream.

Accordingly, there exists a need for a molten metal reactor whichprovides the necessary contact time for converting the carbon materialto the gas product stream and also produces a product gas stream free ofmolten metal.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a molten metal reactor and a method offorming a product gas stream comprising hydrogen, carbon monoxide, andcarbon dioxide using the molten metal reactor. In specific embodiments,the molten metal reactor includes an interior crucible member containedwithin an exterior crucible member. The interior crucible member has aninlet for accepting a feed and an outlet comprising a diffuser.Contained between the interior crucible member and the exterior cruciblemember is at least one baffle. In some embodiments, a filter is alsocontained between the interior crucible member and the exterior cruciblemember. The exterior crucible member includes a vent for venting aproduct gas. In further embodiments, the reactor includes a molten saltcontained between the interior crucible member and the exterior cruciblemember. In still further embodiments, an ion control screen is alsocontained between the interior crucible member and the exterior cruciblemember.

The present invention also relates to a method of forming a product gasstream comprising hydrogen, carbon monoxide, and carbon dioxide usingthe molten metal reactor of the present invention. The method includesfeeding a feed stream comprising a carbon material and steam into theinterior crucible member. The feed stream is diffused through thediffuser at the interior crucible outlet forming vapor bubbles of thefeed stream within the molten alkaline metal compound contained betweenthe interior crucible member and the exterior crucible member. The vaporbubbles react within the molten metal forming a gas comprising hydrogen,carbon monoxide, and carbon dioxide. The vapor bubbles pass through theat least one baffle or travel around the at least one screen baffle toincrease the residence time of the vapor bubbles within the moltenalkaline metal compound. Upon reaching the surface of the moltenalkaline metal compound, the vapor bubbles release a gas comprisinghydrogen, carbon monoxide, and carbon dioxide. In some embodiments, thegas passes through the filter for removing any of the molten alkalinemetal compound from the gas and then the gas exits through the vent. Infurther methods, after the gas passes through the filter, the gas passesthrough an ion control screen for further removing any of the moltenalkaline metal compound in the gas.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming that which is regarded as the present invention,the advantages of this invention may be more readily ascertained fromthe following description of the invention when read in conjunction withthe accompanying drawings in which:

FIGS. 1 through 3 are simplified schematics of a molten metal reactor ofthe present invention.

FIG. 4 is a schematic representation of a method of using the moltenmetal reactor of the present invention.

FIG. 5 is a schematic representation of a molten metal reactor of thepresent invention illustrating three temperature zones of the moltenmetal reactor.

FIG. 6 is a graph representing an example of equilibrium conditionsversus temperature of the first temperature zone in the molten metalreactor of the present invention.

FIG. 7 is a graph representing an example of equilibrium conditionsversus temperature of the second temperature zone in the molten metalreactor of the present invention.

FIG. 8 is a graph representing an example of equilibrium conditionsversus temperature of the third temperature zone in the molten metalreactor of the present invention.

FIG. 9 is a schematic of a molten metal reactor of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Some of the illustrations presented herein are not meant to be actualviews of any particular material, device, or system, but are merelyidealized representations which are employed to describe the presentinvention. Additionally, elements common between figures may retain thesame numerical designation.

The present invention generally relates to a molten metal reactor and amethod of converting a carbon material and steam into a gas comprisinghydrogen, carbon monoxide, and carbon dioxide using the molten metalreactor.

FIG. 1 illustrates a cross-section of one embodiment of a molten metalreactor 100 of the present invention. The molten metal reactor 100comprises two chambers including an inner chamber 101 and an outerchamber 105. The inner chamber 101 is defined by the area inside aninterior crucible member 103, and the outer chamber 105 is defined by anarea between an exterior crucible member 102 and the interior cruciblemember 103. The interior crucible member 103 is entirely containedwithin the exterior crucible member 102 except for an inlet 104 to theinner chamber 101 which extends outside of the exterior crucible member102. The inlet 104 is suitable for directing a feed material into theinner chamber 101. The exterior crucible member 102 includes a vent 106suitable for directing a product gas from the molten metal reactor 100to a suitable treatment means, such as a gas separator, not shown, fortreating the gases formed by the method of the invention. The shape ofthe interior crucible member 103 and the exterior crucible member 102may be any geometrical shape, such as, for example, a cylinder, asquare, or a polygon.

The interior crucible member 103 further includes an outlet 108providing fluid communication between the inner chamber 101 and theouter chamber 105. The outlet 108 may comprise a diffuser 109. Thediffuser 109 is provided to control the rate at which liquids and vaporsenter the outer chamber 105 from the inner chamber 101. In someembodiments, as described in more detail below, liquids and vapors maytravel through the diffuser 109 into a molten alkaline metal compound112. A surface 114 of the molten alkaline metal compound is depicted bya dashed line 114. The diffuser 109 helps control the size of vaporbubbles 204 (FIG. 4) that form in the molten alkaline metal compound 112and also helps to prevent fluctuations in the surface 114 of the moltenalkaline metal compound 112. The diffuser 109 may comprise, for example,a graduated arrangement of inverted weirs and slits, or a series ofholes near the bottom of the inner chamber 101.

Contained within the outer chamber 105 is at least one baffle 116, 116′.In one embodiment, as depicted in FIG. 1, the at least one baffle 116,116′ includes first and third baffles 116 extending from the exteriorsurface of the interior crucible member 103 toward the outer cruciblemember 102 leaving a gap between the first and third baffles 116 and theexterior crucible member 102. A second baffle 116′ extends from theexterior crucible member 102 toward the interior crucible member 103leaving a gap between the second baffle 116′ and the first cruciblemember 103. The second baffle 116′ is positioned between the first andthird baffles 116. While FIG. 1 illustrates three baffles 116, 116′, itis understood that any number of baffles 116, 116′ may be utilized. Thebaffles 116, 116′ prevent large vapor bubbles 204 (FIG. 4) from passingdirectly through the molten alkaline metal compound 112. As such, largevapor bubbles 204 (FIG. 4) will either be broken into smaller vaporbubbles when contacting the baffle 116, 116′, or the vapor bubbles willhave to travel around the serpentine path created by the baffles 116,116′ thus increasing the residence time of the larger vapor bubbles 204(FIG. 4) within the molten alkaline metal compound 112. The baffles 116,116′ may comprise, for example, metal plates or screens. In anembodiment where the baffles 116, 116′ comprise screen baffles, the sizeof the screens may be small enough so that the vapor bubbles 204 (FIG.4) capable of passing through the screens will require only the time ofpassing through the screens to reach the desired rate of conversionwithin the molten alkaline metal compound 112. In a further embodiment,the sizes of the screen of the baffles 116, 116′ may be staggered suchthat screen size of the first screen baffle is larger than the secondscreen baffle and the screen size of the second screen baffle is largerthan the third screen baffle. For example, the first screen baffle mayhave a screen size of between about 3000 microns and about 5000 microns.The second screen baffle may have a screen size of between about 900microns and 2000 microns. The third screen baffle may have a screen sizeof between about 500 microns and 800 microns. Staggering the sizes ofthe screen of the baffles 116, 116′ will help to break up the vaporbubbles 204 (FIG. 4) and decrease the size of the vapor bubbles 204 asthey travel through molten alkaline metal compound 112.

In some embodiments, also contained within the outer chamber 105 is afilter 118. The filter 118 may be provided to remove the molten alkalinemetal compound 112 from gas produced within the molten alkaline metalcompound 112. As the vapor bubbles 204 (FIG. 4) rise to the surface 114of the molten alkaline metal compound 112, the bubbles 204 (FIG. 4) mayburst releasing fine droplets of the molten alkaline metal compound 112within the gas. The filter 118 catches and entrains the molten alkalinemetal compound 112 droplets and allows the molten alkaline metalcompound 121 to drain back to the surface 114 of the molten alkalinemetal compound 112 while allowing the gas, free of the molten alkalinemetal compound 112, to pass through the filter 118. The filter 118 maycomprise, for example, a splash limiter or guard, or a traditionalfiltering means, such as a coalescing filter.

The molten metal reactor 100 may also include a heater 110 positionedadjacent to and/or surrounding the exterior crucible member 102. Theheater 110 provides heat to the molten alkaline metal compound 112 tomaintain the molten alkaline metal compound 112 in a molten state.Additionally, heat sensors, such as thermocouples 120, 122 may bepositioned within the outer chamber 105 for measuring the temperaturetherein. For example, thermocouple 120 may be positioned to measure thetemperature within the molten alkaline metal compound 112, andthermocouple 122 may be positioned to measure the temperature of the gasafter passing through the filter 118.

In further embodiments, as illustrated in FIG. 2, the molten metalreactor 100 may also include an ion control screen 124 within the outerchamber 105. The ion control screen 124 is provided to further reduceand/or eliminate the migration of molten alkaline metal compound ionsout of the molten metal reactor 100. An electric potential of betweenabout 0.5 VDC and 12 VDC may be supplied to the ion control screen 124.The optimal voltage for the ion control screen 124 may depend on thetemperature, pressure, and gas flow rates within the molten metalreactor 100. Lines 126 represent the voltage supplier to the ion controlscreen 124. Any molten alkaline metal compound ions remaining in theproduct gas will be trapped in the ion control screen 124 while theproduct gas passes through the ion control screen 124 and exits themolten metal reactor 100.

In still further embodiments, as illustrated in FIG. 3, the molten metalreactor 100 may include an exterior crucible outlet 128. The exteriorcrucible outlet 128 provides a means for removing and/or inputting themolten alkaline metal compound 112 into the molten metal reactor 100.Periodically, the molten alkaline metal compound 112 may need to beprocessed to remove compounds trapped within the molten alkaline metalcompound 112. Exterior crucible outlet 128 provides a means for removingthe molten alkaline metal compound 112 for processing and then returningthe processed molten alkaline metal compound 112 to the molten metalreactor 100. The molten metal reactor 100 may also include an exteriorcrucible inlet 130. The exterior crucible inlet 130 provides a means forinputting additional steam or other desirable reactants into the moltenmetal reactor 100. If any excess reactants, such as carbon, are presentin the product gas, steam or oxygen may be added through exteriorcrucible inlet 130 to oxidize the excess carbon.

As previously mentioned, in some embodiments, a molten alkaline metalcompound 112 may be provided within the outer chamber 105 of the moltenmetal reactor 100. The molten alkaline metal compound 112 may besuitable for decomposing or pyrolyzing a carbon material into elementalcarbon, while also facilitating the oxidation of the carbon with thesteam to form a gas comprising hydrogen, carbon monoxide, and carbondioxide according to the following reactions:C+H₂O→CO+H₂  Reaction 1CO+H₂O→CO₂+H₂  Reaction 2

All components that come in contact with the molten alkaline metalcompound 112, such as the interior crucible member 103, the exteriorcrucible member 102, and the baffles 116, 116′ are either formed from amaterial which is resistant to damage from the molten alkaline metalcompound 112 or coated with such a protective material.

The molten alkaline metal compound 112 may comprise a mixture of alkalimetal carbonates and hydroxides. Typical examples of suitable alkalimetal compounds are admixtures of: sodium carbonate and sodiumhydroxide; potassium carbonate and sodium hydroxide; sodium carbonateand potassium carbonate; sodium carbonate and lithium carbonate; sodiumcarbonate and potassium hydroxide; sodium carbonate and sodium nitrate;as well as admixtures of more than two compounds, such as mixtures ofthe carbonates of sodium, potassium, and lithium, and mixtures of sodiumcarbonate, sodium hydroxide, and lithium carbonate.

The temperature of the molten alkaline metal compound 112 may be in therange of 400° C. to 1200° C. The preferred temperature of the moltenalkaline metal compound 112 will depend on the components comprising themolten alkaline metal compound 112. For example, if the molten alkalinemetal compound 112 comprises a mixture of sodium carbonate and sodiumhydroxide, the preferred temperature may be about 500° C. to about 950°C. The heater 110 may be adjusted to control the temperature of themolten alkaline metal compound 112. The heater may be capable oftemperatures from, for example, 0° C. to 1900° C. on the outside of theexterior crucible member 102. More specifically, the heater 110 mayoperate at, for example, 600° C. to 1100° C. to maintain the moltenalkaline metal compound 112 within the exterior crucible member 102 at atemperature between about 500° C. and about 950° C. The operatingtemperature of the heater 110 will be dependent on the material,thickness, and size of the exterior crucible member 102.

The molten metal reactor 100 of the present invention may be used toconvert any feed comprising a carbon material and steam into a gascomprising hydrogen, carbon monoxide, and carbon dioxide. The carbonmaterial may comprise any normally liquid hydrocarbons or gaseoushydrocarbons. The term “normally liquid hydrocarbons” as used hereinincludes hydrocarbons whose atmospheric pressure boiling points aregreater than about 38° C. and includes naturally occurring petroleumoils, fractions thereof produced during refining operations, andindividual hydrocarbons. Thus, the carbon-based material may includeacyclic and alicyclic aliphatic hydrocarbons and aromatics such aspentanes, pentenes, hexanes, heptanes, cyclohexanes, benzene, toluene,xylenes, napthalenes, and mixtures thereof. The molten metal reactor 100is especially valuable for the conversion of various normally liquid orliquid-containing petroleum fractions from light to heavy oils and tars.In one embodiment, the carbon-based material may comprise vacuumresidual, a heavy, low-valued carbon material formed as a byproduct ofthe petroleum upgrade process. While the exact composition of the vacuumresidual may vary based on the specifications of the petroleum upgradeprocess, the vacuum residual may typically comprise carbon, hydrogen,sulfur and trace elements. For example, the vacuum residual may have acomposition of approximately 86% carbon, 10% hydrogen, and less than 4%sulfur. Additional examples of the carbon-based material include gasoils including straight run gas oil, thermally cracked gas oil and heavygas oil, cycle oils such as fluid catalytically cracked cycle oil, lightnaptha, heavy naptha, straight run gasoline, kerosene, diesel oil, wholecrude and residual fractions, such as reduced crude. The carbon-basedmaterial may further include, for example, shale oil, tar sand oil,asphalt tar and other liquid-containing heavy or viscous materials,including petroleum waste fractions.

FIG. 4 illustrates one method of forming a gas 206 comprising hydrogen,carbon monoxide and carbon dioxide using the molten metal reactor 100 ofthe present invention. A feed stream 202 comprising a carbon materialand steam is fed into the inlet 104. The feed stream 202 may becontinuously fed into the inlet 104 or the feed stream 202 may be fedinto the inlet 104 in batches. The carbon material in the feed stream202 may be fed to the inlet 104 as a viscous liquid. The feed stream 202may also be pressurized before being fed to the inlet 104. After thefeed stream 202 is fed into the inlet 104, the carbon material mixeswith the steam in the inner chamber 101 forming a mixed feed stream202′. The steam and the heat from the molten alkaline metal compound 112surrounding the inner chamber 101 may vaporize all or portions of thecarbon material, such as for example, volatile components which may bepresent in the carbon material. The mixed feed stream 202′ exits theinner chamber 101 through the diffuser 109 and contacts the moltenalkaline metal compound 112. As the mixed feed stream 202′ contacts themolten alkaline metal compound 112, the mixed feed stream 202′ may formvapor bubbles 204 within the molten alkaline metal compound 112. Thediffuser 109 helps to limit the size of the vapor bubbles 204 that enterthe alkaline metal salt 112. Additionally, the diffuser helps tomaintain the surface 114 of the alkaline metal salt 112 at a steadylevel. As the vapor bubbles 204 pass through the molten alkaline metal112, the molten alkaline metal 112 acts as a catalyst and/or pyrolyzingagent and the feed material reacts forming a gas comprising hydrogen,carbon monoxide, and carbon dioxide. Any impurities in the carbonmaterial, such as, for example, sulfur, may be trapped within the moltenalkaline metal compound 112. As the vapor bubbles 204 pass through themolten alkaline metal 112 they will contact the baffles 116, 116′. Thevapor bubbles 204 will travel around the path formed by the baffles 116,116′. This extended path formed by the baffles 116, 116′ increases theresidence time of larger vapor bubbles 204 within the molten alkalinemetal compound 112, thus providing more time for the vapor bubbles 204to react. The molten metal reactor 100 may be designed such that theresidence time created by the baffles 116, 116′ provides a residencetime long enough for a desired conversion of the carbon material andsteam. This residence time may range from fractions of a second to tensof seconds or longer. As the vapor bubbles 204 reach the surface 114 ofthe molten alkaline metal compound 112, the vapor bubbles 204 may burstreleasing a gas 206 comprising hydrogen gas, carbon monoxide, and carbondioxide. Fine droplets of the molten alkaline metal compound 112 mayalso be in the gas 206. In some embodiments, the gas 206 passes throughthe filter 118 where the droplets of the alkaline metal compound 112 aretrapped. The droplets of the molten alkaline metal compound 112 maydrain from the filter 118 back to the surface 114 of the molten alkalinemetal compound 112. The filtered gas 206′, having the molten saltremoved, exits the filter 118. The filtered gas 206′ may then be removedfrom the molten metal reactor 100 via the vent 106. In furtherembodiments, once the filtered gas 206′ passes through the filter 118,the gas filtered 206′ may pass through the ion control screen 124 whereany remaining alkaline metal ions in the filtered gas 206′ are removed,forming screened gas 206″. Screened gas 206″ may then be removed fromthe molten metal reactor 100 via vent 106.

In some embodiments, as illustrated in FIG. 5, the molten metal reactor100 may be separated into three or more temperature zones: first zone302, second zone 304, and third zone 306. The first zone 302 may also bereferred to as the “reaction zone” and includes the area in the outerchamber 105 comprising the molten alkaline metal compound 112. Thesecond zone 304 may also be referred to as the “separation zone” andincludes the area in the outer chamber comprising the filter 118.Finally, the third zone 306 may also be referred to as the “exit zone”and may include the area of the outer chamber 105 from the filter 118 tothe vent 106 and, additionally, may include piping and systems that maybe connected to the vent 106. The temperature of the first zone 302 maybe the highest temperature of the three zones, followed by the secondzone 304, and then the third zone 306.

FIG. 6 is a graph representing one example of equilibrium conditionsversus temperature for the first zone 302. For this example, the feedstream 202 (FIG. 4) comprises vacuum residual and water. Morespecifically, the feed stream 202 may comprise 0.60 kmol H₂(g), 3.3 kmolH₂O(g), 0.86 kmol C, and 0.015 kmol S. The molten alkaline metalcompound 112 comprises a mixture of sodium hydroxide and sodiumcarbonate. More specifically, the molten alkaline metal compound 112comprises 3.00 kmol Na₂CO₃ and 0.34 kmol NaOH. The temperature of thefirst zone 302 may be about 900° C. and the pressure 1.0 bar. Thetemperature and pressure of the first zone 302 are chosen so that themolten alkaline metal compound 112 is a liquid phase. FIG. 6 illustratesthe equilibrium conditions within the first zone 302 after the feedstream 202 is reacted with the molten alkaline metal compound 112 atvarying temperatures. At 900° C., for example, the equilibriumcompositions are 5.7×10⁻⁵ kmol CH₄(g), 0.506 kmol CO(g), 0.40 kmolCO₂(g), 1.86 kmol H₂(g), 1.91 kmol H₂O(g), 1.07×10⁻⁴ kmol N(g),2.56×10⁻⁴ kmol NaOH(g) and 1.0×10⁻⁸ kmol H₂SO₄*6.5H₂O.

The gases from the first zone 302 exit the molten alkaline metalcompound 112 and enter the second zone 304. FIG. 7 illustrates theequilibrium conditions within the second zone 304. The second zone 304may be maintained at a temperature of, for example, 845° C. At 845° C.,the equilibrium conditions are 1.99×10⁻⁴ CH₄(g), 0.473 kmol CO(g), 0.433kmol CO₂ (g), 1.89 kmol H₂(g), 1.88 kmol H₂O(g), 1×10⁻⁹ kmol H₂SO₄(g),1.87×10⁻⁵ kmol Na(g), and 6.09×10⁻⁵ kmol NaOH(g).

The trace amounts of H₂SO₄, Na, and NaOH, will be trapped within thefilter 118 in the second zone 304 while the CH₄, CO, CO₂, H₂, and H₂Oenter the third zone 306. FIG. 8 illustrates the equilibrium conditionswithin the third zone 306. In the third zone 306, the temperature isfurther decreased and water may be condensed out. The gases may undergoa further shift in composition based on the temperature within the thirdzone 306. The temperature of the third zone 306 will depend on the mostheavily sought product in the gas product stream. For example, ifhydrogen is the most valuable product, the temperature of third zone 306may be approximately 680° C. when the hydrogen composition is thegreatest, as illustrated in FIG. 8.

The molten molten metal reactor 100 of the present invention has severaladvantages over other molten reactors known in the art. For example, thebaffles 116, 116′ within the molten alkaline metal compound 112 increasethe residence time of the carbon material to be converted withoutgreatly increasing the size of the molten metal reactor 100 or thequantity of the molten alkaline metal compound 112. Additionally, thefilter 118 and ion control screen 124 prevent the molten alkaline metalcompound 112 from exiting the molten metal reactor 100 thus avoidingcostly damage to pipes and systems used to process the filtered gas206′.

In further embodiments, the molten metal reactor 100 may be included ina system 400 as illustrated in FIG. 9. In the system 400, a water feed402 and a carbon material feed 404 are fed to a mixer 406. The mixedstreams are then fed into the molten metal reactor 100. The water feed402 and the carbon feed 404 react within the molten metal reactor 100 toform a product stream 408 comprising hydrogen, carbon monoxide, andcarbon dioxide gases. The gases may be sampled at 410 for analysis andcontrol. The process 400 may be monitored by an HMI Monitor and processcontrols 412. The HMI Monitor and process controls 412 are capable ofsending signals for flow and temperature controls 414 of the water feed402 and also signals for flow and temperature controls 416 of the carbonmaterial feed 404.

The invention has been described in language more or less specific as tostructural and methodical features. It is to be understood, however,that the invention is not limited to the specific features shown anddescribed, since the means herein disclosed comprise preferred forms ofputting the invention into effect. The invention is, therefore, claimedin any of its forms or modifications within the proper scope of theappended claims appropriately interpreted in accordance with thedoctrine of equivalents.

What is claimed is:
 1. A molten metal reactor, comprising: an exteriorcrucible member having a vent; an interior crucible member having aportion contained within the exterior crucible member, the interiorcrucible member having an inlet and an outlet, the outlet comprising adiffuser; and a plurality of screen baffles contained between theinterior crucible member and the exterior crucible member, at least oneof the plurality of screen baffles exhibiting a different screen sizethan at least one other of the plurality of screen baffles.
 2. Themolten metal reactor of claim 1, further comprising at least one filtercontained between the interior crucible member and the exterior cruciblemember.
 3. The molten metal reactor of claim 1, further comprising amolten alkaline metal compound contained between the interior cruciblemember and the exterior crucible member.
 4. The molten metal reactor ofclaim 3, further comprising at least one temperature sensor positionedto measure a temperature within the molten alkaline metal compound. 5.The molten metal reactor of claim 1, further comprising at least onetemperature sensor positioned to measure a temperature between theinterior crucible member and the exterior crucible member.
 6. The moltenmetal reactor of claim 1, further comprising an ion control screencontained between the interior crucible member and the exterior cruciblemember and electrically connected to a voltage supplier.
 7. The moltenmetal reactor of claim 1, further comprising a heater adjacent to anexterior surface of the exterior crucible member.
 8. The molten metalreactor of claim 1, further comprising an exterior crucible outlet andan exterior crucible inlet.
 9. A reactor for converting a materialcontaining carbon and steam into a gas comprising hydrogen, carbonmonoxide and carbon dioxide, the reactor comprising: an interiorcrucible member for accepting a feed stream comprising a carbon materialand steam, the interior crucible member having an inlet and an outlet; adiffuser positioned at the outlet of the interior crucible member fordiffusing the feed stream into a molten alkaline metal compound; anexterior crucible member positioned around the interior crucible memberfor containing the molten alkaline metal compound between the interiorcrucible member and the exterior crucible member; baffles located withinthe molten alkaline metal compound contained between the interiorcrucible member and the exterior crucible member for increasing theresidence time of the feed stream within the molten alkaline metalcompound, and comprising: a first screen baffle extending from theinterior crucible member toward the exterior crucible member; a secondscreen baffle extending from the exterior crucible member toward theinterior crucible member and having a smaller screen size than the firstscreen baffle; a third screen baffle extending from the interiorcrucible member toward the exterior crucible member and having a smallerscreen size than the second screen baffle, the second screen bafflepositioned between the first screen baffle and the third screen baffleto form a substantially serpentine path within the molten alkaline metalcompound; and a vent for venting the gas from the exterior cruciblemember.
 10. The reactor of claim 9, further comprising at least onefilter contained between the interior crucible member and the exteriorcrucible member and positioned above a surface of the molten alkalinemetal compound for filtering the gas comprising hydrogen, carbonmonoxide, and carbon dioxide from the molten alkaline metal compound.11. The reactor of claim 9, further comprising an ion control screen forseparating molten alkaline metal ions from the gas.
 12. The reactor ofclaim 9, further comprising a heater located adjacent to the exteriorcrucible member for heating the molten alkaline metal compound.
 13. Thereactor of claim 9, further comprising at least one outlet in theexterior crucible member for removing the molten alkaline metal compoundfrom the exterior crucible member.
 14. The reactor of claim 9, furthercomprising at least one inlet in the exterior crucible member for addingsteam to the exterior crucible member.
 15. A molten metal reactor,comprising: an outer chamber comprising: a first zone having a moltenalkaline metal compound therein, a plurality of screen baffles withinthe molten alkaline metal compound; a second zone adjacent the firstzone and having a filter therein; and a third zone adjacent the secondzone and in communication with a vent; and an inner chamber within theouter chamber and in fluid communication with the first zone of theouter chamber by way of an outlet, at least one of the plurality ofscreen baffles exhibiting a different screen size than at least oneother of the plurality of screen baffles.
 16. The molten metal reactorof claim 15, wherein the molten alkaline metal compound comprises amixture of alkali metal carbonates and hydroxides.
 17. The molten metalreactor of claim 15, wherein the at least one baffle within the moltenalkaline metal compound comprises at least one screen baffle.
 18. Themolten metal reactor of claim 15, wherein the third zone has an ioncontrol screen therein.
 19. The molten metal reactor of claim 1, furthercomprising: a filter between the interior crucible member and theexterior crucible member; and an ion control screen between the filterand the exterior crucible member.